Quantum Handshake Beacon in Communication System Using Bidirectional Quantum Teleportation

Abstract

Network security is essential for communication system. In this paper, we propose a quantum handshake beacon (QHB) protocol based on bidirectional quantum teleportation (BQT) to improve the network security. The BQT scheme for the proposed protocol is designed, including three operators: Alice, Bob and Charlie. Alice and Bob transmit an unknown qubit to each other simultaneously, while Charlie controls the trigger qubits and a Greenberger-Horne-Zeilinger (GHZ) state is shared among them. The qubits to be transmitted as handshake beacon go through different quantum gates and the corresponding unitary transformations are performed on the qubits according to the measurement outcomes. With different trigger qubits, the BQT scheme can achieve unidirectional teleportation with fidelity 1 or bidirectional teleportation with different fidelities. We analyze the fidelity of both sides in BQT with the joint probability of the trigger qubits and point out the area of fidelity over 2/3 classical teleportation limit. In addition, the QHB protocol is proposed for source station and destination station realizing handshake. We define the process of the protocol to illustrate how the protocol works. Based on the fidelity function, we analyze the feasibility of the QHB and verify that the QHB can work well within the maximal retry times in communication protocol. Compared with the unidirectional QHB, the bidirectional QHB has less system average delay.